I am trying to use the SAI driver with MQX 4.2. Looking at the dai_dma_demo example project it seems as simple as calling fopen on the SAI driver and then a call to write. Both of these functions take an MQX_FILE_PTR. It appears that fopen sets up the MQX_FILE_PTR struct but the pointers to IO_WRITE/READ in that struct are null after a call to fopen. I can't find anything in the example code that sets up these function pointers. Are they null because I'm using DMA? Calling write returns MQX_IO_OPERATION_NOT_AVAILABLE
